Ambient audio event detection in a personal audio device headset

ABSTRACT

Ambient audio event detection in a personal audio device headset provides for directive response to external audible events. Depending on the type of event, an alert may be issued, speech may be communicated to another device, program material may be interrupted and/or resumed with or without repositioning, and program material may be modified or selected for compatibility with, or to overcome, the ambient environment indicated by the detected event.

The present U.S. Patent application is a Continuation of U.S. patentapplication Ser. No. 11/367,224 filed on Mar. 3, 2006 now U.S. Pat. No.7,903,825, the disclosure of which is incorporated herein by referenceand from which priority is claimed under 35 U.S.C. §120.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to consumer personal audioplayback devices, and more specifically, to a personal audio playbackdevice that alters the gain of playback program material in response toenvironmental sounds.

2. Background of the Invention

Consumer audio playback devices are in widespread use. Ever since thedevelopment of miniaturized cassette players, portable entertainment haspermitted people to carry around their desired personal listeningmaterial. More recently, miniature players incorporating flash-memory,hard drives and optical storage media to store program material havebeen developed, and some players incorporate LCD screens that permit theviewing of video information along with the associated audio program.

In order to provide the best listening experience, the headphones usedwith present-day personal audio devices have improved to the point thatoutside environmental sounds are attenuated quite severely and thetransducers themselves have improved to provide very high acousticprogram levels from typically low power levels available from suchdevices.

Although the increased loudness and environmental attenuation ispreferable for uninterrupted listening, the possibility of intrusion ofdesirable or sounds indicative of danger has also been reduced. Forexample, it has become increasingly difficult to get the attention of apersonal audio device user in order to converse with them, andconversation between persons using personal audio devices tends to bemutually exclusive of such use. For instance, a person generally mustturn off or extremely attenuate their program material in order toconduct a conversation, or must remove one or both headphone elementsfrom their ears. As another example, a pedestrian listening to audio viasuch a device may not notice a vehicle horn or siren that is alertingthem to a hazard.

One solution to the above-described problems is to use headphoneelements that “leak” more environmental sound into the user's ear, thuspermitting the possibility of the environmental sound overcoming theloudness of the program material. However, the use of more leakyheadphone elements runs contrary to the desired purpose of providing anisolated listening experience. For example, a headphone element thatwill provide enough leakage to alert a pedestrian to a car horn wouldnot be suitable for a person desiring to use the same headphones whilean undesirable environmental noise is present, such as listening whileoperating a vacuum cleaner. Further, with the tendency to increase thevolume of the program material to overcome undesirable noise, damage tohearing becomes an issue, as the human ear is sensitive to prolongedhigh volume levels, whether desirable program material or undesirablenoise.

Recently, the technique of noise cancellation has been applied toconsumer headphones. A microphone detects ambient sounds and a circuitmodifies the program audio electrical signals to attempt to subtract theambient sounds, thus improving the user's listening experience andmaking it less likely that a user will increase the volume of theprogram material to overcome ambient sounds. However, such a device doesnot solve the above-described problems of providing for conversations,and if an environmental noise indicative of a hazard is not sufficientlyloud to as to defeat the noise-canceling mechanism, then the noisecancellation will also not produce a desirable result.

Therefore, it would be desirable to provide a personal consumer audiodevice that provides a quality individual program listening experiencein the presence of environmental noise, while providing forcommunications with others and awareness of environmental soundsindicative of a hazard.

SUMMARY OF THE INVENTION

The above stated objective of providing a quality individual programlistening experience in the presence of environmental noise, whileproviding for communications and hazard awareness is achieved in apersonal audio device.

The device is a headphone unit that includes a processing circuit thatdetects an event in the program material and alters characteristics ofthe program in response to detecting the event. The program material maybe stored within the headphone unit and played back via the processingcircuit and associated converters that provide the headphone signal. Oneor more microphone elements are provided to sense environmental(ambient) sounds and the processing circuit receives a signal from themicrophone elements and alters the program material in response to anevent detected in the microphone signal. The microphone elements may bethe same microphone elements that are increasingly employed to providerecording capability to personal audio devices. The sampling rate andcircuit complexity/power level can be selectively reduced when sensingbackground environmental sounds to prolong battery life, while providingfull bandwidth at high sampling rates during recording or other activityrequiring full audio quality.

The processing circuit may have a selectable operating mode tailored tocontrol the gain of the program material according to a variety ofalgorithms, depending on the expected environment. The gain of theprogram material may be reduced when certain sounds are recognized, suchas sudden noises, vehicle horns or a person attempting to talk to a userof the device. The gain of the program material may be increased inresponse to the level of environmental noise, either overall, or in oneor more particular frequency bands, or the gain may be decreased(including completely attenuated) if a sound is detected to which theuse should be alerted.

The device may include a wireless communications link, such as aradio-frequency (RF) or infrared (IR) link that permits two-waycommunication with a user of another compatible device and the programmaterial gain controlled in conformity with detected incomingtransmissions and the microphone input so that the program material isattenuated or disabled during a conversation period.

The device may intelligently select program material in conformity witha level or characteristic of detected ambient sounds, in order to playprogram material compatible with an environment, either for overcomingenvironmental noises, or in general to select program material likely tobe compatible with a “mood” associated with the environment.

The device may also selectively pause or rewind program material to thepoint at which an interfering sound or conversation is detected orincoming transmission of a wireless conversation.

The foregoing and other objectives, features, and advantages of theinvention will be apparent from the following, more particular,description of the preferred embodiment of the invention, as illustratedin the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a consumer personal audio playback devicein accordance with an embodiment of the present invention.

FIG. 2 is an illustration of a consumer personal audio playback devicein accordance with another embodiment of the present invention.

FIG. 3 is a block diagram depicting internal circuits of a consumerpersonal audio playback device in accordance with an embodiment of thepresent invention.

FIG. 4 is a flowchart depicting operation of a consumer personal audioplayback device in accordance with an embodiment of the presentinvention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENT

The present invention encompasses a consumer personal audio playbackdevice that uses gain control of audio signals rendered frominternally-stored program information to adapt the volume level of aheadphone output to environmental sounds. The gain control is made inconformity with the output of one or more microphone elements integralto the playback device housing that sense environmental sounds and aninternal processing circuit adjusts the gain of the headphone output inconformity with the output of the microphone element(s). The microphoneelement(s) may be the same microphone(s) used to provide recordingcapability when the personal device is also a recorder. The device mayalso include subtractive noise-cancellation as a selectable operatingmode and, if so, the microphones used to provide input to thenoise-cancellation process may be used to provide input to theprocessing circuit of the present invention. Intelligent algorithms areprovided in the processing circuit to analyze the environmental soundsand adjust the gain of the headphone outputs in one or more frequencybands in conformity with the results of the analysis.

Referring now to FIG. 1, a consumer personal audio playback device inaccordance with an embodiment of the present invention is shown. Aretaining arm 11 is attached to a device housing 10 for retaining devicehousing 10 to a wearer's ear. An output audio transducer 12 is includedon housing 10 to provide audio program information to the wearer fromprogram media stored within housing 10. A microphone element 17 isdisposed within housing 10 and acoustically coupled through the surfaceof housing 10 to detect environmental sounds. However, microphone 17 mayalternatively be connected to the device via external wiring, so thatthe microphone can be located in another location, for example, near thewearer's mouth. A microphone boom (not shown) may be included for thatpurpose. Another output audio transducer 12A is connected to the devicevia a wired connection 13 extending external to housing 10 and anothermicrophone element 17A may be included in the packaging of output audiotransducer 12A and connected via wired connection 13 as well. A wired orwireless connection 15 to a remote control 14 provides for control ofthe playback of audio program information via controls 16A and a display18. Alternatively, or in combination, controls 16 may be included on thesurface of device housing 10. Callout 18A shows details of an exemplaryselection screen of display 18 in which device mode selections are madeby scrolling through the listed options. Selection can be mutuallyexclusive, or overlapping via enable/disable selections.

Referring now to FIG. 2, a consumer personal audio playback device inaccordance with another embodiment of the present invention is shown. Adevice housing 20 contains the stored program material and circuits forproviding an audio signal to a set of headphones, that include at leastone audio output transducer 12A and optionally an associated microphoneelement 27 or elements (one positioned at each ear of a wearer). Aconnector 25 provides connection of the headphones at the exteriorsurface of device housing 20. Multiple connectors 25 may be used toconnect microphone element(s) 27, or the connections may be combined inone connector 25. Alternatively, or in combination, microphone element27A may be provided at and acoustically coupled through the surface ofdevice housing 20. A display 28 and controls 26 are also provided at thesurface of device housing 20 to control the playback of audio programmaterial. Callout 28A shows details of an exemplary selection screen ofdisplay 28 in which device mode selections are made by scrolling throughthe listed options. Selection can be mutually exclusive, or overlappingvia enable/disable selections.

While both of the above-depicted embodiments are particular presentforms of consumer audio playback devices, such depictions are notlimiting, but exemplary, and the present invention applies in general todevices that provide audio playback of media stored within the devicevia a headset intended to isolate a wearer acoustically from externalsounds, at least to some degree of attenuation. The present inventionprovides a mechanism for either overcoming leakage of external soundsthat can and should be ignored, and providing control of the gain of theaudio program playback when external sounds should not be ignored.Further, while the present invention and this disclosure are directedprimarily toward audio playback, devices in accordance with the presentinvention can also be personal video playback devices or game units, andthe techniques disclose and claimed herein extend to the processing ofaudio information provided by the video or game sources.

Referring now to FIG. 3, a block diagram of electrical circuits withinthe above-described consumer personal audio playback devices is shown.Audio program storage 32, which as mentioned above can include the audioportion of video program material or computer program-generated audiosources such as game or Musical Instrument Device Interface (MIDI)information playback, provides the program source material. For digitalaudio playback devices, storage 32 will generally be a FLASH memory,magnetic disc or optical disc or array that encodes binaryrepresentations of audio as compressed or uncompressed numericalinformation. Processing circuit 34 performs gain control and renderingof the program information retrieved from storage 32 and provides theresult to a digital-to-analog converter (DAC) 35 that converts theprocessed program information to analog form that is provided to aheadphone amplifier 36A connected to headphones via a connector 25B orvia a direct connection as shown above with respect to the device ofFIG. 1.

Microphone element 27A and/or microphone connector 25A provides one ormore electrical signals corresponding to environmental sounds that areamplified by preamplifier 36 and converted via an analog-to-digitalconverter (ADC) 38 to digital information provided to processing circuit34. While the depicted circuits are digital in nature, the presentinvention can include direct gain control of the output of DAC 35 via ananalog level detection of the output of preamplifier 26 or otherprocessing of the program by analog means, including analog multi-bandcompression. The sampling rate and bandwidth of the microphone signalcan be set much lower than that used for recording in personal devicesin order to save power. Further, the measurements can be madeperiodically, with ADC 36 and preamplifier 36 shut down betweenmeasurement intervals in order to conserve battery power.

Control circuit 33 has a power control output coupled to preamplifier 26and/or ADC 38 that can selectively adjust the power consumption ofpreamplifier 26 and/or ADC 38 by changing the type of amplifier employedas preamplifier 26 or altering bias currents, as well as adjusting thesampling rate and/or bit depth of ADC 38. ADC 38 and preamplifier 26also may be disabled when microphone input is not required and/orperiodically enabled when only periodic monitoring is required. Whilebackground noise and sounds are being monitored, a lower sampling rateand bit depth of ADC 38 can be employed, and lower performance can betolerated from preamplifier 26. Multiple power levels can be supportedso that when the personal device is operating in one of the conversationmodes described below, an intermediate power level may be selected forconversations, a low power level may be selected for monitoring thebackground, and a high power level may be selected for recording modes.

Controls 26 are connected to control circuit 33, which is generally amicrocontroller or microprocessor with program and data storage memory,for controlling the playback of the stored program information andselectable operating mode of the consumer personal audio device as willbe described in further detail below. Display 28 is coupled to controlcircuit 33 to provide menus for operating the device, and may alsoprovide playback of stored video information. Processing circuit 34 isgenerally a digital signal processor with data and program memory, aswell, and may be the same processor as control circuit 33. A battery 37supplies power to the internal circuits of the consumer personal audiodevice.

A wireless link circuit 39 is coupled to a transducer 31, which may bean antenna or infrared transducer, for providing communication withexternal remote control devices such as remote control 14 of FIG. 1, orcommunication with other personal audio playback or other devices asprovided in some of the operating modes described below. Further, thewired connection of headphones and microphone elements as describedabove may be replaced with completely wireless communications viawireless link 39, with suitable amplification circuits and transceiverslocated within the microphone/headphone element packages. Wireless linkcircuit 39 may also provide input to processing circuit 34 and/orcontrol circuit 33 for control of the gain of audio program materialrendered from storage 32 in certain operating modes of processingcircuit 34 as will be described in further detail below.

Compressor Mode

As mentioned above, there are multiple operating modes that theabove-described consumer personal audio devices can enter, and theparticular algorithm used to control the gain of the audio programmaterial will vary depending on the selected mode. In the most basic“compressor” mode, selected to overcome environmental sounds in general,the gain of low levels of program audio is adjusted upward in conformitywith the detected loudness of the external sounds. Processing circuit 34acts as an electronic volume control that increases the gain of theprogram audio as ambient noise increases. However, the gain of higherlevels of program audio are not increased linearly, but are adjustedaccording to a “soft knee” compression curve that causes lessincremental increase in program material for larger increases in ambientnoise as higher levels of audio are reached.

Compressor mode is particularly useful with “leaky” headphones and willprovide adjustment of volume so that in quiet environments, a low levelof volume of the program audio is produced, while in noisy environments,a higher level of volume is produced, up to a safety limit, which mayeither be set by the design of headphone amplifier 36A, an outputresistance of the headphone circuit, or the limiting action of theabove-described compression curve provided by the mode processingalgorithm employed in the selected mode.

Multi-Band Compressor Mode

A multi-band compressor mode, which may be selectable or may be the onlyexpander mode implemented within the personal device, provides morehearing protection while overcoming environmental noise by analyzing themicrophone signal provided by ADC 38, to detect the loudness of theenvironmental noise in multiple frequency bands. The detected levels ofloudness are used to control compression of the program material gain inmultiple frequency bands by splitting the program material intocorresponding frequency bands and independently controlling the gain ofthe signal provided in each band to DAC 35. The loudness of the programmaterial in each frequency band can also be detected, and a combinationof the loudness of the program material and the detected environmentalnoise level in each band can be used to control the gain of the signalsupplied to DAC 35 in each frequency band.

The frequency bands can be selected according to the Bark scale ofhearing discrimination, the Mel scale, or other suitable set of bands.Table 1 shows psycho-acoustic equalization algorithm gain increasevalues that can be provided in look-up tables or implemented incontinuous control functions in order to accomplish the above-describedgain control. Table 2 shows the corresponding resultant output levelsfrom the gain processing algorithm or circuit (compressor). Thecompressor is a variable-ratio compressor, with the ratio set by thelevel of the background noise, so that for larger levels of backgroundnoise, smaller gains are applied, i.e., the amount of compression isincreased. For example, in the left-hand column corresponding to arelative background noise level of 20 dB, changes in program material of10 dB yield changes in the gain of 2 dB, and thus output level changesof 8 dB (a 1.25:1 compression slope). In the extreme right-hand column,10 dB changes in program material yield 8 dB changes in gain and thus 2dB changes in output level (a 5:1 compression ratio).

TABLE 1 Applied Gain Value program Background noise level level 20 dB 30dB 40 dB 50 dB 60 dB 70 dB 80 dB 100 dB  0  0  0  0  0  0  0  90 dB  2 3  4  5  6  7  8  80 dB  4  6  8 10 12 14 16  70 dB  6  9 12 15 18 2124  60 dB  8 12 16 20 24 28 32  50 dB 10 15 20 25 30 35 40  40 dB 12 1824 30 36 42 48  30 dB 14 21 28 35 42 49 56  20 dB 16 24 32 40 48 56 64

TABLE 2 Resulting Output Level program Background noise level level 20dB 30 dB 40 dB 50 dB 60 dB 70 dB 80 dB 100 dB 100 dB 100 dB 100 dB 100dB 100 dB 100 dB 100 dB  90 dB  92 dB  93 dB  94 dB  95 dB  96 dB  97 dB 98 dB  80 dB  84 dB  86 dB  88 dB  90 db  92 dB  94 dB  96 dB  70 dB 76 dB  79 dB  82 dB  85 dB  88 dB  91 dB  94 dB  60 dB  68 dB  72 dB 76 dB  80 dB  84 dB  88 dB  92 dB  50 dB  60 dB  65 dB  70 dB  75 dB 80 dB  85 dB  90 dB  40 dB  52 dB  58 dB  64 dB  70 dB  76 dB  82 dB 88 dB  30 dB  44 dB  51 dB  58 dB  65 dB  72 dB  79 dB  86 dB  20 dB 36 dB  44 dB  52 dB  60 dB  68 dB  76 dB  84 dB

The above-described multi-band compression mode algorithm avoids theproblems of merely increasing overall gain that may result inunnecessary clipping or an increase in volume above safe listeninglevels in order to overcome background noise. As mentioned above, themulti-band compression mode (or the single-band compression mode) can beimplemented by a signal processing algorithm according to programinstructions stored within a memory of processing circuit 34 or bydedicated circuits.

Personal Safety Mode

Another useful mode that is implemented by a signal processing algorithmaccording to program instructions stored within a memory of processingcircuit 34 or a dedicated circuit is a personal safety mode. In personalsafety mode, sudden changes in volume, or particular frequency patternssuch as vehicle horns or loud voices, are detected and processingcircuit 34 either partially or completely attenuates the programmaterial gain, so that a user of the personal audio playback device willhear the outside sounds. The microphone input can be provided at theheadphone output and/or mixed with the program audio, so that the useris made more aware of the external environment while the sound ispresent, and optionally for some time thereafter according to a timerand timing value implemented by processing circuit 34.

Social Mode

Similar to the personal safety mode, in social mode, also implemented bya signal processing algorithm according to program instructions storedwithin a memory of processing circuit 34 or a dedicated circuit, speechof another person is detected and the program material is attenuated, sothat a user of the personal audio playback device can converse withanother person. The microphone input can be provided at the headphoneoutput and/or mixed with the program audio, so that the user is able tohear the other person quite well without requiring removal of headphoneelements. A timer can be used to restore the program material after aperiod without speech by either the user or the other person isdetected.

Environment Match Mode

In yet another mode, implemented in an algorithm of processing circuit34 and/or control circuit 33, a type of outside environment isdetermined by analyzing the output of ADC 38 for loudness, frequencycharacter and other clues such as pattern matching. Program material canbe selected from storage 32 in conformity with the detected environmentin order to play back a compatible program. For example, automotivesounds might cause selection of rock music, quiet environments mightselect New Age music, and conversation might select rap music. Suchselection may set a compatible mood in the user and/or more effectivelymask external sounds.

Linked Chat Mode

Similar to conversation mode, in chat mode, also implemented by a signalprocessing algorithm according to program instructions stored within amemory of processing circuit 34 or a dedicated circuit, speech of theuser (wearer) is detected and transmitted to another device via wirelesslink 39. The program material is paused or attenuated for both devicesuntil a timer has expired and the other device can transmit audioinformation directly from the other device's microphone circuits to thedevice of FIG. 3, so that the other device-user's speech is sent toheadphone amplifier 36A and connected headphone elements.

Review Mode

Another mode provided by the personal audio playback device of thepresent invention, is a review mode in which a portion of storage 32 oranother memory is dedicated to storing the ADC 38 output in a FIFObuffer. If a portion of the preceding external sounds (such as alecture) is missed, the contents of the buffer can be reviewed viacontrols 26 that provide for reviewing the program material.

In personal safety mode, social mode and linked chat mode, as well asany other modes for which the program material would otherwise beinterrupted or severely attenuated, a sub-mode can be implemented inwhich the program material is either paused at or rewound to the pointat which the interruption began, so that the program material is notmissed. Such a sub-mode is particularly useful when listening to suchmaterial as “books on tape”, lectures or other informational programsources.

In each of the above modes where the character of external environmentalsounds is being determined, the use of multiple microphones, such asmicrophone elements 17 and 17A, provides for the possibility ofdetermining the direction of the environmental sound source. In such animplementation, it is possible to determine whether a person speaking orother sound is coming from the space directly in front of theuser/wearer and selection of activation of such modes as social mode orlinked chat mode made in conformity with the determination. Also, themode can be initiated in this manner, and then subsequently maintained,so that two persons can walk astride while the mode is continued.

Further, each of the above-described modes, as well as a defaultplayback and optionally a default recording mode may be selectablemanually via controls, or as noted above for some modes such as theconversation modes, e.g. linked chat and social modes may beautomatically engaged (when enabled) upon detecting the appropriateindication from the environment or from another device. Additionally,personal safety mode or either of the expander modes might bepermanently and simultaneously implemented without a control fordisabling the feature. Most of the above-described modes are also notmutually exclusive and therefore can be engaged at one time. Whilecompression mode will generally be single or multi-band, the other modescan be implemented simultaneously in a single device and each may beselectively enabled without interfering with the others as illustratedbelow.

Referring now to FIG. 4, operation of the above-described personalconsumer audio playback devices is shown in a flowchart. The acousticenvironment is monitored either periodically or continuously asdescribed above (step 50). If environment match mode is enabled(decision 51), then environmentally-compatible program material isselected for playback (step 52), otherwise, normal user or randomselection of program material is made (step 53). The selected programmaterial is played (step 54) and if a compression mode is selected(decision 55), the gain of the program material is adjusted in one ormore frequency bands in conformity with the detected background noiselevel (step 56),

If an event responsive mode is selected (decision 57), then the devicewill respond to an ambient audio or wireless event by attenuating,pausing or discontinuing playback of the program material and replacingit in the audio output with event-related material (step 58). Forexample, in linked chat mode the program material is replaced with thewireless received speech, in social and personal safety modes, theprogram material is replaced with the sounds received by the devicemicrophone(s). A predetermined time after the event has passed, theprogram material is repositioned and/or resumed (step 59). Untilplayback is complete, or the device is disabled (decision 60), theambient audio environment is continually monitored and theabove-described steps repeated.

While the invention has been particularly shown and described withreference to the preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in form,and details may be made therein without departing from the spirit andscope of the invention.

What is claimed is:
 1. A headphone unit for portable consumer audioplayback device use, the headphone unit comprising: an audio programsource for providing audio program information; an audio outputtransducer for generating an acoustic output from an audio output signalcontaining the audio program information; a microphone for sensingambient sounds external to the headphone unit and producing an ambientmeasuring audio signal; an audio processor that detects an event in theambient sounds from the ambient measuring audio signal, determines acharacteristic of the event, and in response, selects a type of programmaterial provided from the audio program source for compatibility withthe event to generate the audio output signal, wherein the audioprocessor selects the type of the program material for acousticcompatibility with the ambient sounds corresponding to the event to seta mood or more effectively mask the ambient sounds corresponding to theevent; and a battery for supplying power to the audio processor.
 2. Theheadphone unit of claim 1, wherein the audio processor, responsive todetecting the event, pauses playback of the audio program informationand resumes playback of the audio program information after thedetecting of the event has ended.
 3. The headphone unit of claim 1,further comprising a wireless receiver for receiving the audio programinformation from an external device containing a program source.
 4. Theheadphone unit of claim 1, wherein the audio processor furtherdistinguishes a characteristic of the event as a sound to which a wearerof the headphone unit should be alerted, and wherein the audio processordelivers the ambient sounds to the audio output signal and attenuatesthe audio program information while the event is present.
 5. Theheadphone unit of claim 4, wherein the processor distinguishes the eventas speech when the audio processor is in a mode selected as a socialmode, whereby conversations can be conducted with a wearer of theheadphone unit.
 6. The headphone unit of claim 4, wherein the audioprocessor distinguishes the event as a hazard indication when theprocessor is in a mode selected as a personal safety social mode,whereby a wearer of the headphone unit is alerted to the hazardindication.
 7. The headphone unit of claim 1, further comprising atransceiver for communicating with another audio reproduction deviceequipped with a receiver, wherein the audio processor distinguishes theevent as speech of a wearer of the headphone unit, and wherein the audioprocessor delivers the ambient measuring audio signal to the transceiverfor transmission to the other audio reproduction device in response tothe audio processor distinguishing the event as speech, when the audioprocessor is in a mode selected as a linked chat mode.
 8. The headphoneunit of claim 1, further comprising at least one other microphone,wherein the audio processor further detects a directionality of theevent and wherein the altering of the program information is furtherqualified by the detected directionality.
 9. A method of processingaudio program information in a headphone unit, the method comprising:providing an audio program source within the headphone unit forgenerating the audio program information; within the headphone unit,generating an acoustic output from an audio output signal containing theaudio program information; sensing ambient sounds external to theheadphone unit producing an ambient measuring audio signal; within theheadphone unit, detecting an event in the ambient sounds from theambient measuring audio signal; responsive to detecting the event,determining a characteristic of the event; and within the headphoneunit, responsive to determining the characteristic of the event,selecting a type of program material for compatibility with the event asthe audio program information used to generate the audio output signal,wherein the selecting selects the type of the program material foracoustic compatibility with the ambient sounds corresponding to theevent to set a mood or more effectively mask the ambient soundscorresponding to the event.
 10. The method of claim 9, furthercomprising: responsive to detecting the event, pausing playback of theaudio program information; and resuming playback of the audio programinformation after the detecting of the event has ended.
 11. The methodof claim 9, further comprising receiving the audio program informationfrom an external device containing a program source via a wireless link.12. The method of claim 9, further comprising: distinguishing acharacteristic of the event as a sound to which a wearer of theheadphone unit should be alerted; and delivering the ambient sounds tothe audio output signal and attenuating the audio program informationwhile the event is present.
 13. The method of claim 12, wherein thedistinguishing distinguishes the event as speech when the audioprocessor is in a mode selected as a social mode, whereby conversationscan be conducted with a wearer of the headphone unit.
 14. The method ofclaim 12, wherein the distinguishing distinguishes the event as a hazardindication when the processor is in a mode selected as a personal safetysocial mode, whereby a wearer of the headphone unit is alerted to thehazard indication.
 15. The method of claim 9, further comprising:communicating with another audio reproduction device equipped with areceiver; distinguishing the event as speech of a wearer of theheadphone unit; and delivering the ambient measuring audio signal to thetransceiver for transmission to the other audio reproduction device inresponse to distinguishing the vent as speech, when the audio processoris in a mode selected as a linked chat mode.
 16. The method of claim 9,further comprising detecting a directionality of the event, and whereinthe altering of the program information is further qualified by thedetected directionality.